目录

案例三

需求

​​​​​​​编码步骤

​​​​​​​代码实现-方式1

​​​​​​​代码实现-方式2

​​​​​​​案例三

需求

使用Flink SQL来统计5秒内 每个用户的 订单总数、订单的最大金额、订单的最小金额

也就是每隔5秒统计最近5秒的每个用户的订单总数、订单的最大金额、订单的最小金额

上面的需求使用流处理的Window的基于时间的滚动窗口就可以搞定!

那么接下来使用FlinkTable&SQL-API来实现

​​​​​​​编码步骤

1.创建环境

2.使用自定义函数模拟实时流数据

3.设置事件时间和Watermaker

4.注册表

5.执行sql-可以使用sql风格或table风格(了解)

6.输出结果

7.触发执行

​​​​​​​代码实现-方式1

      package cn.itcast.sql;
      import lombok.AllArgsConstructor;
      import lombok.Data;
      import lombok.NoArgsConstructor;
      import org.apache.flink.api.common.eventtime.WatermarkStrategy;
      import org.apache.flink.api.java.tuple.Tuple2;
      import org.apache.flink.streaming.api.datastream.DataStream;
      import org.apache.flink.streaming.api.datastream.DataStreamSource;
      import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
      import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
      import org.apache.flink.table.api.Table;
      import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
      import org.apache.flink.types.Row;
      import java.time.Duration;
      import java.util.Random;
      import java.util.UUID;
      import java.util.concurrent.TimeUnit;
      import static org.apache.flink.table.api.Expressions.$;
      /**
       * Author itcast
       * Desc
       */
      public class FlinkSQL_Table_Demo04 {
          public static void main(String[] args) throws Exception {
              //1.准备环境
              StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
              StreamTableEnvironment tEnv = StreamTableEnvironment.create(env);
              //2.Source
              DataStreamSource<Order> orderDS  = env.addSource(new RichSourceFunction<Order>() {
                  private Boolean isRunning = true;
                  @Override
                  public void run(SourceContext<Order> ctx) throws Exception {
                      Random random = new Random();
                      while (isRunning) {
                          Order order = new Order(UUID.randomUUID().toString(), random.nextInt(3), random.nextInt(101), System.currentTimeMillis());
                          TimeUnit.SECONDS.sleep(1);
                          ctx.collect(order);
                      }
                  }
                  @Override
                  public void cancel() {
                      isRunning = false;
                  }
              });
              //3.Transformation
              DataStream<Order> watermakerDS = orderDS
                      .assignTimestampsAndWatermarks(
                              WatermarkStrategy.<Order>forBoundedOutOfOrderness(Duration.ofSeconds(2))
                                      .withTimestampAssigner((event, timestamp) -> event.getCreateTime())
                      );
              //4.注册表
              tEnv.createTemporaryView("t_order", watermakerDS,
                      $("orderId"), $("userId"), $("money"), $("createTime").rowtime());
              //5.执行SQL
              String sql = "select " +
                      "userId," +
                      "count(*) as totalCount," +
                      "max(money) as maxMoney," +
                      "min(money) as minMoney " +
                      "from t_order " +
                      "group by userId," +
                      "tumble(createTime, interval '5' second)";
              Table ResultTable = tEnv.sqlQuery(sql);
              //6.Sink
              //将SQL的执行结果转换成DataStream再打印出来
              //toAppendStream → 将计算后的数据append到结果DataStream中去
              //toRetractStream  → 将计算后的新的数据在DataStream原数据的基础上更新true或是删除false
              DataStream<Tuple2<Boolean, Row>> resultDS = tEnv.toRetractStream(ResultTable, Row.class);
              resultDS.print();
              env.execute();
          }
          @Data
          @AllArgsConstructor
          @NoArgsConstructor
          public static class Order {
              private String orderId;
              private Integer userId;
              private Integer money;
              private Long createTime;
          }
      }
  
 

toAppendStream → 将计算后的数据append到结果DataStream中去

toRetractStream  → 将计算后的新的数据在DataStream原数据的基础上更新true或是删除false

​​​​​​​代码实现-方式2

      package cn.itcast.sql;
      import lombok.AllArgsConstructor;
      import lombok.Data;
      import lombok.NoArgsConstructor;
      import org.apache.flink.api.common.eventtime.WatermarkStrategy;
      import org.apache.flink.api.java.tuple.Tuple2;
      import org.apache.flink.streaming.api.datastream.DataStream;
      import org.apache.flink.streaming.api.datastream.DataStreamSource;
      import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
      import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
      import org.apache.flink.table.api.Table;
      import org.apache.flink.table.api.Tumble;
      import org.apache.flink.table.api.bridge.java.StreamTableEnvironment;
      import org.apache.flink.types.Row;
      import java.time.Duration;
      import java.util.Random;
      import java.util.UUID;
      import java.util.concurrent.TimeUnit;
      import static org.apache.flink.table.api.Expressions.$;
      import static org.apache.flink.table.api.Expressions.lit;
      /**
       * Author itcast
       * Desc
       */
      public class FlinkSQL_Table_Demo05 {
          public static void main(String[] args) throws Exception {
              //1.准备环境
              StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
              StreamTableEnvironment tEnv = StreamTableEnvironment.create(env);
              //2.Source
              DataStreamSource<Order> orderDS = env.addSource(new RichSourceFunction<Order>() {
                  private Boolean isRunning = true;
                  @Override
                  public void run(SourceContext<Order> ctx) throws Exception {
                      Random random = new Random();
                      while (isRunning) {
                          Order order = new Order(UUID.randomUUID().toString(), random.nextInt(3), random.nextInt(101), System.currentTimeMillis());
                          TimeUnit.SECONDS.sleep(1);
                          ctx.collect(order);
                      }
                  }
                  @Override
                  public void cancel() {
                      isRunning = false;
                  }
              });
              //3.Transformation
              DataStream<Order> watermakerDS = orderDS
                      .assignTimestampsAndWatermarks(
                              WatermarkStrategy.<Order>forBoundedOutOfOrderness(Duration.ofSeconds(2))
                                      .withTimestampAssigner((event, timestamp) -> event.getCreateTime())
                      );
              //4.注册表
              tEnv.createTemporaryView("t_order", watermakerDS,
                      $("orderId"), $("userId"), $("money"), $("createTime").rowtime());
              //查看表约束
              tEnv.from("t_order").printSchema();
              //5.TableAPI查询
              Table ResultTable = tEnv.from("t_order")
                      //.window(Tumble.over("5.second").on("createTime").as("tumbleWindow"))
                      .window(Tumble.over(lit(5).second())
                              .on($("createTime"))
                              .as("tumbleWindow"))
                      .groupBy($("tumbleWindow"), $("userId"))
                      .select(
                              $("userId"),
                              $("userId").count().as("totalCount"),
                              $("money").max().as("maxMoney"),
                              $("money").min().as("minMoney"));
              //6.将SQL的执行结果转换成DataStream再打印出来
              DataStream<Tuple2<Boolean, Row>> resultDS = tEnv.toRetractStream(ResultTable, Row.class);
              resultDS.print();
              //7.excute
              env.execute();
          }
          @Data
          @AllArgsConstructor
          @NoArgsConstructor
          public static class Order {
              private String orderId;
              private Integer userId;
              private Integer money;
              private Long createTime;
          }
      }
  
 

文章来源: lansonli.blog.csdn.net，作者：Lansonli，版权归原作者所有，如需转载，请联系作者。

原文链接：lansonli.blog.csdn.net/article/details/116357554